# App Search Boosts explained

**URL:** <https://discuss.elastic.co/t/app-search-boosts-explained/355149>\
**Category:** Elastic Search\
**Tags:** elastic-app-search\
**Created:** [March 11, 2024, 11:48am UTC](https://discuss.elastic.co/t/app-search-boosts-explained/355149 "2024-03-11T11:48:35Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Chenko](https://avatars.discourse-cdn.com/v4/letter/c/258eb7/32.png) [@Chenko](https://discuss.elastic.co/u/Chenko)\
**Post date:** [March 11, 2024, 11:48am UTC](https://discuss.elastic.co/t/app-search-boosts-explained/355149/1 "2024-03-11T11:48:35Z")

</div>

Could someone please check if my current understanding of how boosts work in app search is correct.

 ![full_scripts&expl](https://us1.discourse-cdn.com/elastic/original/3X/2/7/27580d6b093eaae45aca8d05f00f7375212914e9.jpeg)

I also cannot get a "script" to generate when using the search\_explain api, on the proximity boosts. I wanted to do this to see how the boost is calculated in code. How would these look in that script format?

I already checked the following documentation: [relevance tuning guide](https://www.elastic.co/guide/en/app-search/current/relevance-tuning-guide.html#relevance-tuning-guide-weights-and-boosts-boost-concepts)

Thanks,  
Chenko

---

<div class="post-metadata">

**Author:** ![ioana.tagirta](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/ioana.tagirta/32/46368_2.png) [@ioana.tagirta](https://discuss.elastic.co/u/ioana.tagirta)\
**Post date:** [March 12, 2024, 9:49am UTC](https://discuss.elastic.co/t/app-search-boosts-explained/355149/2 "2024-03-12T09:49:57Z")

</div>

> I also cannot get a "script" to generate when using the search\_explain api, on the proximity boosts. I wanted to do this to see how the boost is calculated in code. How would these look in that script format?

The proximity boost is done differently.  
Taking the [proximity boost example](https://www.elastic.co/guide/en/app-search/current/boosts.html#boosts-proximity-boosts) from the documentation, we can use the search\_explain API with the sample `national-parks-demo` engine:

```auto
curl -X GET 'http://localhost:3002/api/as/v1/engines/national-parks-demo/search_explain' \
-H 'Content-Type: application/json' \
-H 'Authorization: Bearer private-[REDACTED]' \
-d '{
  "boosts": {
    "location": {
      "type": "proximity",
      "function": "linear",
      "center": "25.32, -80.93",
      "factor": 8
    }
  },
  "query": "old growth"
}'

```

If we take the Elasticsearch query from the response:

```auto

GET .ent-search-engine-documents-national-parks-demo/_search
{
  "query": {
    "bool": {
      "must": {
        "function_score": {
          "boost_mode": "sum",
          "score_mode": "sum",
          "query": {
            "bool": {
              "must": [
                {
                  "bool": {
                    "should": [
                      {
                        "multi_match": {
                          "query": "old growth",
                          "minimum_should_match": "1<-1 3<49%",
                          "type": "cross_fields",
                          "fields": [
                            "world_heritage_site^1.0",
                            "world_heritage_site.stem^0.95",
                            "world_heritage_site.prefix^0.1",
                            "world_heritage_site.joined^0.75",
                            "world_heritage_site.delimiter^0.4",
                            "description^2.4",
                            "description.stem^2.28",
                            "description.prefix^0.24",
                            "description.joined^1.8",
                            "description.delimiter^0.96",
                            "title^5.0",
                            "title.stem^4.75",
                            "title.prefix^0.5",
                            "title.joined^3.75",
                            "title.delimiter^2.0",
                            "nps_link^0.7",
                            "nps_link.stem^0.665",
                            "nps_link.prefix^0.07",
                            "nps_link.joined^0.525",
                            "nps_link.delimiter^0.28",
                            "states^2.8",
                            "states.stem^2.66",
                            "states.prefix^0.28",
                            "states.joined^2.1",
                            "states.delimiter^1.12",
                            "id^1.0"
                          ]
                        }
                      },
                      {
                        "multi_match": {
                          "query": "old growth",
                          "minimum_should_match": "1<-1 3<49%",
                          "type": "best_fields",
                          "fuzziness": "AUTO",
                          "prefix_length": 2,
                          "fields": [
                            "world_heritage_site.stem^0.1",
                            "description.stem^0.24",
                            "title.stem^0.5",
                            "nps_link.stem^0.07",
                            "states.stem^0.28"
                          ]
                        }
                      }
                    ]
                  }
                }
              ]
            }
          },
          "functions": [
            {
            "linear": {
              "location.location": {
                "origin": "25.32, -80.93",
                "scale": "1km"
              }
            },
            "weight": 8
            }
          ]
        }
      }
    }
  },
  "sort": [
    {
      "_score": "desc"
    },
    {
      "_doc": "desc"
    }
  ],
  "highlight": {
    "fragment_size": 300,
    "type": "plain",
    "number_of_fragments": 1,
    "order": "score",
    "encoder": "html",
    "require_field_match": false,
    "fields": {}
  },
  "size": 10,
  "from": 0,
  "timeout": "30000ms",
  "_source": [
    "visitors",
    "square_km",
    "world_heritage_site",
    "date_established",
    "description",
    "location",
    "id",
    "acres",
    "title",
    "nps_link",
    "states"
  ]
}

```

The proximity boost is a separate function that is being passed to the `function_score` query:

```auto
{
  "linear": {
    "location.location": {
      "origin": "25.32, -80.93",
      "scale": "1km"
    }
  },
  "weight": 8
}

```

---

<div class="post-metadata">

**Author:** ![ioana.tagirta](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/ioana.tagirta/32/46368_2.png) [@ioana.tagirta](https://discuss.elastic.co/u/ioana.tagirta)\
**Post date:** [March 12, 2024, 9:56am UTC](https://discuss.elastic.co/t/app-search-boosts-explained/355149/3 "2024-03-12T09:56:52Z")

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> [@Chenko](#):
>
> Could someone please check if my current understanding of how boosts work in app search is correct.

looks right!  
to give more context, we always want to ensure that the score the script returns is positive, since Elasticsearch does not allow for negative scores - if the script score would return a negative value, Elasticsearch would return an error. That's why we always use `Math.max(..., 0)`.

---

<div class="post-metadata">

**Author:** ![Chenko](https://avatars.discourse-cdn.com/v4/letter/c/258eb7/32.png) [@Chenko](https://discuss.elastic.co/u/Chenko)\
**Post date:** [March 12, 2024, 10:02am UTC](https://discuss.elastic.co/t/app-search-boosts-explained/355149/4 "2024-03-12T10:02:42Z")

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> [@ioana.tagirta](#):
>
> looks right!  
> to give more context, we always want to ensure that the score the script returns is positive, since Elasticsearch does not allow for negative scores - if the script score would return a negative value, Elasticsearch would return an error. That's why we always use `Math.max(..., 0)`.

Thanks for the confirmation and additional information!

---

<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [April 9, 2024, 10:03am UTC](https://discuss.elastic.co/t/app-search-boosts-explained/355149/5 "2024-04-09T10:03:24Z")

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